18665728 has 36 divisors (see below), whose sum is σ = 39459420. Its totient is φ = 8781824.

The previous prime is 18665683. The next prime is 18665729. The reversal of 18665728 is 82756681.

It can be written as a sum of positive squares in 2 ways, for example, as 16257024 + 2408704 = 4032^2 + 1552^2 .

It is not an unprimeable number, because it can be changed into a prime (18665729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2208 + ... + 6496.

It is an arithmetic number, because the mean of its divisors is an integer number (1096095).

Almost surely, 2^18665728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18665728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19729710).

18665728 is an abundant number, since it is smaller than the sum of its proper divisors (20793692).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18665728 is an equidigital number, since it uses as much as digits as its factorization.

18665728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4322 (or 4308 counting only the distinct ones).

The product of its digits is 161280, while the sum is 43.

The square root of 18665728 is about 4320.3851680145. The cubic root of 18665728 is about 265.2660340134.

The spelling of 18665728 in words is "eighteen million, six hundred sixty-five thousand, seven hundred twenty-eight".